---
id: "CVE-2017-9791"
kind: "vulnerability"
aliases: ["CVE-2017-9791"]
title: "Apache Struts 1: Apache Struts 1 Improper Input Validation Vulnerability"
severity: "critical"
cvss: 9.8
epss: 0.98908
exploited: true
status: "open"
category: "runtime"
products: [{"name": "Apache Struts 1", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["apache-struts", "exploited", "java", "runtime", "self-hosted"]
not_affected_if: ["struts-1-not-deployed"]
published_at: "2017-07-10T16:29:00+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2017-9791", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2017-9791", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2017-9791", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Apache Struts 1: Apache Struts 1 Improper Input Validation Vulnerability

The Struts 1 plugin in Apache Struts 1 can be made to run code on the server when a crafted field value is passed in a raw message to ActionMessage. An attacker who sends such a request can execute commands with the privileges of the application.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Apache Struts 1 affected ? fixed ?

## Fix

Apply updates per vendor instructions; the sources do not name a fixed version.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2017-9791
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2017-9791
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2017-9791

## From the sources

The Struts 1 plugin in Apache Struts might allow remote code execution via a malicious field value passed in a raw message to the ActionMessage.

CISA required action: Apply updates per vendor instructions.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_